The present invention relates to an apparatus for activating an on-board vapor recovery system which is designed to capture vapor emissions which may occur during the act of refueling and which may also occur as the result of running loss. Specifically, the purpose of the invention is to provide a vacuum or low pressure signal to a diaphragm actuated control valve which in turn will actuate a refueling vapor recovery system. This invention is particularly useful with the refueling vapor recovery system which is the subject of copending patent application Ser. No. 713,402 filed Jun. 10, 1991. The subject matter of the '402 patent application is expressly incorporated herein.
The capture of hydrocarbon vapor being expelled during the act of refueling and hydrocarbon vapor which is created during motor vehicle operations is a government mandated technology designed to ensure that no hydrocarbon vapor will be released to the atmosphere from the motor vehicle. Therefore, a primary concern in motor vehicle design is the ability to capture the hydrocarbon vapor being released from the fuel tank during the act of refueling and the fuel vapor released as the result of motor vehicle running loss. A variety of valves and vent systems, all designed to transmit fuel vapor to an appropriate storage container such as a carbon canister, have been designed and perform these stated objectives with varying degrees of efficiency. These system control valves are commonly designed to remain closed or to route fuel vapor to a separate storage canister, thereby providing and maintaining a certain vapor pressure within the fuel system. If the vapor pressure exceeds a given level, the relief valves are designed to open and expel the buildup of fuel vapor within the tank system. Usually the signal to open the relief valve comes from a control mechanism, responsive to high pressure, which can be separate from the relief valve or made a part thereof. Such control mechanisms commonly comprise the use of mechanical switches, seals, floats and sometimes openings to the atmosphere, all of which are prone to malfunction. Also, the use of such mechanisms as mechanical switches, seals, and three-way valves require that the mechanisms be packaged in the filler pipe or tank assembly and that they be activated by either removing the filler cap or inserting a fuel nozzle. Thus, in order to prevent unnecessary complications and breakdowns in the vapor recovery system, it is desirable to simplify the actuation of the fuel vapor control valve. The present invention intends to simplify and improve upon the complexities presented by current control valves.